Add the mayonnaise, dairy-free milk, rice vinegar, garlic, onion powder, salt, and pepper to a small blender and blend until completely combined. Note: if you don’t have a small blender such as a Magic Bullet, you can mix all of the ingredients together in a small bowl. Just be sure to finely mince the garlic first.
Stir the chopped chives, parsley, and dill into the dressing until well combined.
Taste the dressing for flavor and add more sea salt, pepper, or vinegar to taste.
Store dressing in an airtight jar or airtight container in the refrigerator for up to 1 week.